On 29 August 2010, I hiked to Clouds Rest from Happy Isles trail head in Yosemite National Park. At 20-miles round-trip and 6000 ft total elevation gain, it was a challenging day hike. It took me 6 hours to reach the top and 4.5 hours to descend.
Traihead: Happy Isles trailhead, close to Curry Village.
9.6 miles to Clouds Rest via Mist Trail: From Happy Isles trail head (4,035 ft) → 0.8 miles to Vernal Falls Bridge → 0.7 miles to top of Vernal Falls (5,044 ft) → 1.3 miles to restrooms near Nevada Falls (5,908 ft) → 2.5 miles to fork (2.0 miles to Half Dome on left; 4.3 miles to Clouds Rest on right) → 4.3 miles to Clouds Rest.
10.5 miles to Happy Isles via John Muir Trail: Follow the above route back until you reach the restrooms near Nevada Falls. Then hike 0.2 miles to Nevada Falls, cross the bridge and continue 3.5 miles along John Muir Trail to reach Happy Isles trailhead.
Notes: There are two routes for reaching the restrooms near Nevada Falls. The shorter (2.8 miles) but steeper route is through Mist Trail, which offers amazing views of Vernal Falls. In spring, soon after rains, water is aplenty, making the stony trial wet and slipper (caution is warranted) and there's always a rainbow. The longer (3.7 miles) route avoids Vernal Falls completely. It has a series of switchbacks and should be preferred for the return journey — gentler gradient is better for your knees.
1. Happy Isles Trailhead
We started from Happy Isles at 7:15am. We parked our car at a parking lot that was about half a mile away from the trail head. We followed an unnamed trail to reach a paved road. The road soon crossed Merced river via a bridge. Immediately after the bridge, we took a right towards Happy Isles trail head. From the trail head, Clouds Rest is 10.5 miles away if you go by John Muir Trail. It is only 9.5 miles away if you go by the shorter but steeper Mist Trail.
About 2.8 miles into the hike, we reached Nevada Falls. The last portion of the hike involves a series of switchbacks with stony steps. There's a restroom at Nevada Falls. A sign reminded us that Clouds Rest was 6.8 miles ahead.
Half Dome is seen quite clearly along John Muir Trail. Views from atop Clouds Rest are spectacular. You can see the entire Yosemite Valley. There's a ridge next to Clouds Rest. It's not really a "knife edge" — it's several feet wide everywhere.